Triggering

[km03ki]

Hi there,

I've been attempting to establish a worksheet with a pre/post trigger to record both voluntary contractions and elicited twitch contractions via EMG.  I have been trying just about everything and having little success.  What I would like to do is set up 2 worksheets, one for the voluntary, and one for elicited, each being triggered by a force trace, then recording baseline for 1.0 seconds before, and 1.0 seconds after the respective contraction.  My problem is that whenever I employ one of the triggers, either pre/post, or the combi trigger, the output I read in MATlab gives me a constant value of 5.0.  I've read a document saying that the trigger mode produces square waves?? Is this true, I'm looking to essentially perform the action of the Combi Trigger, but have the data in the window be a representation of the waveform associated with the force trace, and the resulting EMG traces.  Any input on this would be much appreciated.  I have made a few worksheets, and can attach them if that would help.

DASYLab 10.0

6 Channels, triggering off 1 channel

1.0 sec pre & post trigger

voluntary: minimum duration: 5 seconds

twitch: minimum duration: 1 second

Thanks!

-  Kyle

[Now_With_Underscores]

Hey Kyle,

Go ahead and post your worksheets.  Also, post screenshots of the output you're seeing so we can get some more info about your setup.  Have a great evening!

[km03ki]

hi John,

the forum will not let me post the worksheet, do you have an email I can send it to?

Kyle

[Now_With_Underscores]

Hey Kyle,

With your permission I can contact you via the email address you've provided to the forum.

[CJ_Butler__DASYLab_Pro]

It would also be interested to see the raw data, before triggering and any scaling. I usually recommend that you collect a file with DDF data. Often the trigger settings will trigger on the noise in the signal. Depending on the data, you can do something to reduce noise (filter, average) or, set the trigger high enough to be sure of the event, and set the pre-trigger value to catch the data leading up to the event.

The other trigger module that may be interesting is the Combi Trigger, if you have DASYLab Basic or higher. 

[km03ki]

hi there,

you can definitely contact me via email, would be much appreciated.  I have some figures showing our EMG trace, as well as our Force trace, and an example of one of our twitches.  I will send these via email, along with the worksheet I've prepared when you contact myself via my forum linked email.

I've tried working with the combi trigger and same results as before; the data I'm interested in comes out as a square wave.  Our lab is unfortunately closed tomorrow at noon til January 2nd, I will still have access to email, but unfortunately any possible solutions will not be able to be implemented until after the new year.  Thanks again for your help CJ and John, I really appreciate it.

Kyle

[CJ_Butler__DASYLab_Pro]

I think that this is resolved.

The Trigger modules create a control signal, either 0 or 5, which is what you were seeing. The control signal should be used to control the data flow through the relay, and the inputs to the Relay should be data channels. 

By adding another display module (Chart Recorder or Y/t Chart) on the other side of the Relay, you can confirm that you are seeing "triggered" data, rather than the trigger signal itself.